Recently, biologic characteristic identification, such as fingerprint identification, vein identification, iris identification, or the like, are used more and more widely for personal information confirmation due to better information security. A Lens assembly with good optical characteristic and a narrow view angle range is normally desired in biologic characteristic identification to ensure identification accuracy.
The lens assembly disclosed in Japanese patent publication No. 2007-147830 includes a first lens with negative refractive power and a second lens with positive refractive power. However, a view angle of the lens assembly is too wide and is inapplicable to biologic characteristic identification.
The lens assembly disclosed in Japanese patent publication No. 2013-218353 includes a first lens and a second lens. However, the distribution of the refractive power of the first lens and the second lens, the proportion of the central thickness of the first lens to the focal length of the lens assembly, the proportion of the axial distance from the image side of the first lens to the object side of the second lens to the focal length of the lens assembly are not fully. So the view angle of the lens assembly is too wide and is inapplicable to biologic characteristic identification.
The lens assembly disclosed in Japanese patent publication No. 2012-108449 includes a first lens and a second lens. However, the distribution of the refractive power of the first lens and the second lens, the proportion of the cenreal thickness of the first lens to the focal length of the lens assembly, the shape of the first lens are not fully. So the view angle of the lens assembly is too wide and is inapplicable to biologic characteristic identification.
Accordingly, an improved lens assembly for biologic characteristic identification which can overcome the disadvantages described above is desired.